Connunications update following Polls:

[The Local Ned]

Signals are intercepted on transmit - not on receive.

Basically the RF 'detector' unit will give an indication of the bearing where your signal is strongest from. It will then move position and await your next transmission and do the same again....once it has 3 separate plots - where those lines converge roughly gives your position.

This can then enable door to door or grid searches to happen in that general area.

[Paul]

Most any superhet receivers transmit RF signal on receive but only a tiny tiny bit.

They have a little circuit in called a local oscillator.
In my old CB it ran 10.7 Mhz lower than the channel I was listening to. (or was it higher?)

Gives you an idea of what I'm talking about.

That signal is detectable and was what the old TV detector vans zeroed in on in Busby days (when naughty CBers were tracked down shot and stuffed as trophy's.)

Typical single DF accuracy of 30 feet over 100 yards.

It's also what some "RF bug sniffers" on scanners happily latch onto today.

Again close range unless you are using a really good handheld directional antenna but typically a maximum of 200 yards if there is absolutely nothing else on in the neighborhood.

My modern microprocessor based CB set is terrible at transmitting spurious RF signals though as does my PC.

It seems that the more modern the gear, the worse "noise" it generates.

That's modernization for you.

Gawd I love valves!

[Lightspeed]

Paul's right, all receivers have a local oscillator. And many other electrical gadgets too

These include:
Transistor radios for AM/FM/LW broadcasts
Mobile telephones
Electronic calculators
Televisions
Digital cameras
Computers
Sat Navs
Kindles
Digital clocks
Quartz wrist watches

The list goes on and on and on. Radio is at the heart of much of todays high technology.

But the radio output from these oscillators is tiny.

Who's going to be listening for these tiny signals post SHTF? I'd say no one at all.

And today, with so many devices giving off similar levels of local oscillator radio noise, it'd be quite difficult to find an individual CB receiver. And again, who's looking.... no one at all.

When constructing radios I sometimes have to listen for Local oscillator tone. The reality is that even out of its shielded metal box, and using a sensitive receiver 10 to 15 feet is the realistic range from which I can detect it. Once the radio is in its metal box this shields the Local oscilator and it can only be detected from a few feet away.

I'd say not to wory about being DF'd if you are just using a CB to receive. If someone's really looking so hard to find you that they are going to the trouble of Direction Finding Local oscillator signals, there will be plenty of easier ways for them to find you (noise, smell, heat, smoke, refuse etc)

[PrepperJohn]

Thanks Guys that was really interesting.

The more I learn about radio, the more there is to learn

[Paul]

I've been working with electronics and radio for over 40 years and still don't get it all.
It's a fascinating hobby which the old timer radio hams loved.
Now, all you need is a credit card and a TINY bit of training to become a ham.

It's no wonder there is such a conflict going on between the old timer hams and the "M" lot.

You know a lot of people knock CB but that's how a lot of hams started off.
Funny bit about it is when they get their "ticket", it must come with a little brainwashing program, as a lot of the ex-CB'ers soon start slagging off us old time CB breakers.

Someone on the forum mentioned once that CB isn't expandable. Not adventurous enough.
That's where ham radio comes in.

What they forgot was CB has a 'naughty' cousin called the Free Banders.
Working with modified CB or even ham sets, they wander round the HF bands (mainly 10 and 11m) chatting away right round the world.
Some of those folk know more than most hams have forgotten.
Only difference is they haven't sold their souls for a piece of paper.

There is a well known saying Free Banders use,
"There's a big spectrum out there".

Loads of interesting people, using every mode possible, mostly dead friendly and helpful, and for some reason the mortal enemy of the ham world.

Not that I'm biased though.

11Mike962 signing off, 10.10

[Lightspeed]

PJ and Paul,

My facsination with radio is that NOBODY understands completely how propogation works. Its all theories and models.

The truth is, no one exactly understands how a few miliwats of RF power can be heard on the other side of the planet. (to give a comparison, by a few miliwats I mean less than half the power consumed by the very smallest peanut bulb in a car's dash board lighting)

Its a pity that some folk who first gained an interest in radio through CB change their attitude when they get their ham licenses. We're all radio enthusiasts, and a dying breed at that. Ham/ CB/ Freebanding are just different flavours of the same thing.

Me, I'm not fussy, I'll talk to anyone...... and sometimes people answer me too! :-)

[PrepperJohn]

Well I am one of the M lot so I suppose I am going to get abused by the CB crowd for being a snob and the ham crowd for not being good enough.

PJ

[Lightspeed]

(4 October 2012, 13:22)PrepperJohn Wrote: Well I am one of the M lot so I suppose I am going to get abused by the CB crowd for being a snob and the ham crowd for not being good enough.

PJ

I think it depends where in in the country you are PJ.

Paul has endured some stupidity from Hams in his area.

Personally I come from the CB blood line and in the areas I operate, I've never had any problems either with Amateurs, nor CBers. Maybe I've just been lucky.

Nothing wrong with an M3 or M6 c/s. A friend of mine is a VERY experienced naval radio operator ( retired) His thing is CW, but he has no need of greater power or privileges than is permitted with his M3 C/S. He is completely content as an M3 and has great fun with smart asses who try tease him in morse, wrongly assuming him to be a newbee, only to find themselves completely outgunned by his skills:-)

Good for you getting your license. Hope you are enjoying the airwaves.

LS

[PrepperJohn]

Thanks LS

I am enjoying it.I have only been on air for a few weeks so it is all very new. I have signed up for the intermediate course which will hopefully be in February next year.

I am learning morse at the moment because I want to explore qrp and building my own equipment etc

Ham equipment is so expensive.

[Lightspeed]

(4 October 2012, 15:25)PrepperJohn Wrote: Thanks LS

I am enjoying it.I have only been on air for a few weeks so it is all very new. I have signed up for the intermediate course which will hopefully be in February next year.

I am learning morse at the moment because I want to explore qrp and building my own equipment etc

Ham equipment is so expensive.

Hi PJ,

Yes ham gear ( the proper stuff) is extremely expensive.

Re Morse, its a good skill to have. Find yourself an enthusiastic Ham to help you learning.... I'm not very proficient but good enough to manage some quick QRP contacts on home built kit.... I would not have achieved even this low level of skill without the encouragement and advice of a mentor.

It too late for this year, but have a look at the RSGB backpacker competition. I used to take part in this with a 30 year old Yaesu FT 290 Mk1 2.5w contacts to Scotland and Central Europe through home made portable yagi antennas are a real thrill.......The prepping element to this is that its great cover for going onto the hills to test equipment and operating methods in the real world......that experience continues to benefit me to this day. Getting sensitive electronica to work consistently in wet, windy and cold conditions is a great challenge. ( the Summits On The Air SOTA program is equally good in this respect)

When you have rigs that can operate on 40m and 80m CW let us know as there are a number of folk on this forum who are gearing up for low power CW operations as part of their preps. When we have sufficient number we will be able to start regular CWtraining nets as part of establishing part of the Prepper communications network.

72 de

LS